diff --git a/extensions/observability-devservices/common/src/main/java/io/quarkus/observability/common/ContainerConstants.java b/extensions/observability-devservices/common/src/main/java/io/quarkus/observability/common/ContainerConstants.java
index f815c77415331..bb50ac4513475 100644
--- a/extensions/observability-devservices/common/src/main/java/io/quarkus/observability/common/ContainerConstants.java
+++ b/extensions/observability-devservices/common/src/main/java/io/quarkus/observability/common/ContainerConstants.java
@@ -13,5 +13,6 @@ public final class ContainerConstants {
     public static final int OTEL_GRPC_EXPORTER_PORT = 4317;
     public static final int OTEL_HTTP_EXPORTER_PORT = 4318;
 
+    public static final String OTEL_GRPC_PROTOCOL = "grpc";
     public static final String OTEL_HTTP_PROTOCOL = "http/protobuf";
 }
diff --git a/extensions/observability-devservices/testcontainers/src/main/java/io/quarkus/observability/testcontainers/LgtmContainer.java b/extensions/observability-devservices/testcontainers/src/main/java/io/quarkus/observability/testcontainers/LgtmContainer.java
index f218711b137cc..a56d503128121 100644
--- a/extensions/observability-devservices/testcontainers/src/main/java/io/quarkus/observability/testcontainers/LgtmContainer.java
+++ b/extensions/observability-devservices/testcontainers/src/main/java/io/quarkus/observability/testcontainers/LgtmContainer.java
@@ -41,7 +41,8 @@ public LgtmContainer() {
 
     public LgtmContainer(LgtmConfig config) {
         super(config);
-        addExposedPorts(getOtlpPortInternal());
+        // always expose both -- since the LGTM image already does that as well
+        addExposedPorts(ContainerConstants.OTEL_GRPC_EXPORTER_PORT, ContainerConstants.OTEL_HTTP_EXPORTER_PORT);
         // cannot override grafana-dashboards.yaml in the container because it's on a version dependent path:
         // ./grafana-v11.0.0/conf/provisioning/dashboards/grafana-dashboards.yaml
         // will replace contents of current dashboards
@@ -69,8 +70,14 @@ public int getOtlpPort() {
     }
 
     private int getOtlpPortInternal() {
-        return ContainerConstants.OTEL_HTTP_PROTOCOL.equals(getOtlpProtocol()) ? ContainerConstants.OTEL_HTTP_EXPORTER_PORT
-                : ContainerConstants.OTEL_GRPC_EXPORTER_PORT;
+        // use ignore-case here; grpc == gRPC
+        if (ContainerConstants.OTEL_GRPC_PROTOCOL.equalsIgnoreCase(getOtlpProtocol())) {
+            return ContainerConstants.OTEL_GRPC_EXPORTER_PORT;
+        } else if (ContainerConstants.OTEL_HTTP_PROTOCOL.equals(getOtlpProtocol())) {
+            return ContainerConstants.OTEL_HTTP_EXPORTER_PORT;
+        } else {
+            throw new IllegalArgumentException("Unsupported OTEL protocol: " + getOtlpProtocol());
+        }
     }
 
     private String getPrometheusConfig() {
diff --git a/extensions/observability-devservices/testlibs/devresource-lgtm/src/main/java/io/quarkus/observability/devresource/lgtm/LgtmResource.java b/extensions/observability-devservices/testlibs/devresource-lgtm/src/main/java/io/quarkus/observability/devresource/lgtm/LgtmResource.java
index 281e5ac26ebe5..2c835036c789d 100644
--- a/extensions/observability-devservices/testlibs/devresource-lgtm/src/main/java/io/quarkus/observability/devresource/lgtm/LgtmResource.java
+++ b/extensions/observability-devservices/testlibs/devresource-lgtm/src/main/java/io/quarkus/observability/devresource/lgtm/LgtmResource.java
@@ -53,21 +53,23 @@ protected LgtmContainer defaultContainer() {
     @Override
     public Map<String, String> doStart() {
         String host = container.getHost();
+        int otlpPort = container.getOtlpPort();
 
         //Set non Quarkus properties for convenience and testing.
         Map<String, String> containerConfigs = new HashMap<>();
         containerConfigs.put("grafana.endpoint", String.format("http://%s:%s", host, container.getGrafanaPort()));
-        containerConfigs.put("otel-collector.url", String.format("%s:%s", host, container.getOtlpPort()));
+        containerConfigs.put("otel-collector.url", String.format("%s:%s", host, otlpPort));
 
         // set relevant properties for Quarkus extensions directly
         if (catalog != null && catalog.hasOpenTelemetry()) {
-            containerConfigs.put("quarkus.otel.exporter.otlp.endpoint",
-                    String.format("http://%s:%s", host, container.getOtlpPort()));
+            containerConfigs.put("quarkus.otel.exporter.otlp.endpoint", String.format("http://%s:%s", host, otlpPort));
             containerConfigs.put("quarkus.otel.exporter.otlp.protocol", container.getOtlpProtocol());
         }
         if (catalog != null && catalog.hasMicrometerOtlp()) {
+            // always use http -- as that's what Micrometer supports
             containerConfigs.put("quarkus.micrometer.export.otlp.url",
-                    String.format("http://%s:%s/v1/metrics", host, container.getOtlpPort()));
+                    String.format("http://%s:%s/v1/metrics", host,
+                            container.getMappedPort(ContainerConstants.OTEL_HTTP_EXPORTER_PORT)));
         }
         return containerConfigs;
     }
diff --git a/integration-tests/observability-lgtm/src/test/java/io/quarkus/observability/test/LgtmGrpcTest.java b/integration-tests/observability-lgtm/src/test/java/io/quarkus/observability/test/LgtmGrpcTest.java
new file mode 100644
index 0000000000000..ef7cf1595f4aa
--- /dev/null
+++ b/integration-tests/observability-lgtm/src/test/java/io/quarkus/observability/test/LgtmGrpcTest.java
@@ -0,0 +1,26 @@
+package io.quarkus.observability.test;
+
+import java.util.Map;
+
+import org.junit.jupiter.api.condition.DisabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+
+import io.quarkus.test.junit.QuarkusTest;
+import io.quarkus.test.junit.QuarkusTestProfile;
+import io.quarkus.test.junit.TestProfile;
+
+/**
+ * Simple case were we use gRPC as a OTLP protocol
+ */
+@QuarkusTest
+@TestProfile(LgtmGrpcTest.GrpcTestProfileOnly.class)
+@DisabledOnOs(OS.WINDOWS)
+public class LgtmGrpcTest extends LgtmTestBase {
+
+    public static class GrpcTestProfileOnly implements QuarkusTestProfile {
+        @Override
+        public Map<String, String> getConfigOverrides() {
+            return Map.of("quarkus.observability.lgtm.otlp-protocol", "grpc");
+        }
+    }
+}